The traditional optimal allocation of water resources cannot reflect the specific water distribution of a water consumption unit. To resolve the issue, an improved model for the optimal allocation of water resources was developed in combination with the existing gridding concept and remote sensing technologies to minimize water scarcity and maximize economic benefit. This model incorporates the water supply scopes and water users of the water sources in a region in the form of cells, using multiple water resources, objectives, and users in the region as the base points. Further, the Particle Swarm Optimization (PSO) algorithm was employed to solve this model. The results reveal as follows: First, the northeast, west, and southeast areas of Guantao County have the lowest water demands, while the east lower-middle half has the greatest. Second, it is estimated that in the years of the plan (P = 50%), the county’s total water demand will be 118,871,900 m 3, which can be met by the total available water supply (125,281,800 m 3); the economic benefit will reach 4,086,500 Yuan in the target year of the plan. Third, the region refined water resources optimizing the allocation is favorable to lowering groundwater exploitation, coping with the water resources deficit, and promoting the rational allocation and management of water resources.